The ferrules on the lower spreader have been a problem. I actually switched mine out - I created a full length lower spreader from the same carbon rod and switched over to that.
That is a great idea. How do you connect your self made lower spreader to the spin? I simply put some superglue on lower spreaders where they connect to the center T and make them a bit bigger diameter for tighter fit. If it is too tight, just use sandpaper sand them down a bit until tight fit is achieved. They do not come apart so far.
Close - I just took the bit of a standoff that goes around the rod and cut off the standoff part and put it on the center of the carbon rod (with glue as well). Then, I put the centerT connector in hot water until I could shove the standoff section into it. It's very secure - many hours flyign now and it does not move.
Your idea is essentially the same. I have used your technique on female lower spreaders than get worn down from friction inside the rod mostly due to sand I am guessing. Build it up with 4-5 thin layers of CA and it fits tight as new.